The Kartchner Caverns, a limestone cave system beyond the reach of sunlight and seemingly devoid of life, boast an unexpected diversity of microorganisms that rival microbial communities on the earth's surface, they said.
Though tiny, the microbes constitute thriving communities of life, they said.
"We discovered all the major players that make up a typical ecosystem," said researcher scientist Julie Neilson of the university's College of Agriculture and Life Sciences. "From producers to consumers, they're all there, just not visible to the naked eye."
DNA swabbed from stalactites and other cave formations allowed the researchers to identify the bacteria and archaea -- single-celled microorganisms that lack a cell nucleus -- living in the cave.
"We didn't expect to find such a thriving ecosystem feasting on the scraps dripping in from the world above," Neilson said. "What is most interesting is that what we found mirrors the desert above: an extreme environment starved for nutrients, yet flourishing with organisms that have adapted in very unique ways to this type of habitat."
"It shows the flexibility of microbes," she said. "They have conquered every niche on the planet."